Radio tunning apparatus



April 9, 1935. A. A. THCMAS RADIO TUNING APPARATUS Filed Dec. 10, 1923 Sheets-Sheet 1 VOLUM E April 9, 1935. A. A. THOMAS RADIO TUNING APPARATUS 4 Sheets-Sheet 2 Filed Dec. 10, 1929 INVENTOR IIIIMM April 9', 1935. A THOMAS 1,997,158

RADI O TUNING APPARATUS Filed Dec. 10, 1929 Sheets-Sheet 3 April 9, 1935. A. A. THOMAS RADIO .TUNING APPARATUS Filed Dec. 10, 1929 4 Sheets-Sheet 4 lillimmlmmnu )Illllllllllll llllllllllll INVENTOR Patented Apr. 9, 1935 UNITED STATES FATENT OFFICE 20 Claims.

My invention relates to the art of radio reception and its object is to provide a simple compact device for controlling the operation of a radio receiver from a distance to tune in any selected station. In a preferred form of my invention, the control device also includes a thermostatic time switch for automatically turning off the radio receiver after a predetermined interval. All the parts can be housed a small oblong box which is operatively connected to the receiver by an electric cable. As will appear later, the mechanism in the control box comprises but few parts, which are cheap to make, easy to assemble, and not liable to get out of order.

A slidable key or button on top of the control box moves along an indicator for selecting any desired station. When the button is pushed down, certain electric circuits are closed to actuate the tuning shaft of the receiver until the selected station is in tune. A knob on the box permits the control of tone volume, and a switch enables the operator to shut off the set at any time. This switch may also be controlled by a thermostat to open all circuits after a predetermined lapse of time. The operation of the thermostat is controlled by a timing knob which regulates the passage of current through a heating coil mounted on the thermostat. When the timing knob is set, a person is assured that the receiver will be automatically turned off after so many minutes. This makes it safe for a person to go to sleep to the soft sound of radio music as children especially like to do. A signal light on the box may be used to indicate when the time control is on. If remote control is not desired, my novel tuning device may be mounted directly on the radio cabinet. In either case, the receiver is always free to be tuned by hand in the old way.

The foregoing and other practical advantages and novel features of my control box will be understood from a description of the accompanying drawings, in which Fig. 1 shows a top view of a remote control device embodying my invention;

Fig. 2 is an inside plan view of the box on section line 2- 2 of Fig. 3;

Fig. 3 represents a transverse section on line 3-53 of Fig. 1;

Fig. i is a fragmentary longitudinal section through the box on line i- 't of Fig. 3;

Fig. 5 shows an enlarged fragmentary view along the broken line 55 of Fig. 3;

Fig. 6 is a detached enlarged perspective of contact fingers operated by the push button on the box;

Fig. '7 is a section on line 'l-l of Fig. 2, to show a side View of the snap-over switch member operable either by hand or by a timed thermostat; 5

Fig. 8 shows a vertical section through the timing knob and associated parts;

Fig. 8a is an enlarged section on line 8a-Ba of Fig. 8, except that the signal lamp is omitted for clearness;

Fig. 9 shows a plan View of the tuning condensers and associated operating mechanism in the radio receiver;

Fig. 10 is a side View of Fig. 9 looking from left to right;

Fig. 11 represents a side view on line i I-H of Fig. 10;

Fig. 11a is a fragmentary face View of an insulating support carrying station-selecting contacts which are radially adjustable for any station;

Fig. 11b is a section on line i lb-l lb of Fig. 11a;

Fig. 12 is a section on line l2-l2 of Fig. 9, showing a detail of the intermittent bevel gear connection between the motor shaft and the tuning shaft;

Fig. 13 shows a section on line i3l3 of Fig. 11 to illustrate certain details of the electromagnetic clutch between the motor shaft and the shaft on which the bevel gears in Fig. 9 are mounted;

Fig. 14 is a side view of the motor switch and associated electromagnet; and

Fig. 15 is a diagram of circuit connections between the receiver and the remote control box.

Referring to Fig. l, the remote control box it] is provided on top with a longitudinal slot i2 through which projects a shank l3 carrying a push button M. The shank i3 is slidably mounted so that the push button M is slidable along a station indicator on top of the box. In the present instance this indicator comprises a series oi. marks or lines 55 representing ten selected stations, which are identified by the letters A to K. The push button id, which is removably attached to shank l3 by a set-screw it, has a pointer ll 45 arranged to be brought in register with any one of the station marks 25. After a station has been selected by sliding the push button l4 to proper position, the button is depressed to close certain operating circuits for rotating the tuning shaft of the connected radio receiver. When the selected station is in tune, the radio shaft is automatically stopped and the operator releases button l. These circuits and the operating mechanism controlled thereby will be fully explained in due course.

Still referring to-Fig. 1, a finger piece l3 projects through a slot is to operate a suitable onoif switch in the control box. It is assurned that the finger piece in is in on position when the button M is operated to tune in a station. A rotary knob 26 permits regulation of the volume of reproduction as desired. In a preferred form of my invention, the remote control box if) is provided with a rotary knob 25 for controlling a time switch to shut off the radio receiver automatically after a predetermined interval. A pointer 22 movable with knob 25 cooperates with a time scale 23, which I have arbitrarily marked with seven periods representing minutes, but any other suitable division of time may be employed. When the pointer 22 is on the oil mark 26, the time switch is disconnected.

I shall now describe the mechanism inside of box ill, and for this purpose reference will be had to Figs. 2-854. The bottom of box i ii is formed by an insulating base 35, which may conveniently be cast or molded as one piece from suitable material, such as bakelite, porcelain, hard rubber, and others along the same line. If the base 25 is of metal, such as aluminum, it will be necessary to provide separate insulation for the electric contacts carried by the base. For this reason it is simpler to make the base of insulating material. The upper or cover part of the box may be stamped from a single piece of sheet metal and removably secured to base 25 by screws 25 or otherwise. The cover part of the box is not attached to the base until all the mechanism inside the box has been properly assembled. After'the box is closed, the hand-operable parts i i, 28, 2c and 2| are attached to their respective supports. Two pairs of posts or brackets 21 project upwardly from base 25, and may be formed integral therewith. The posts 27 are provided with slots or recesses 28 for receiving the ends of a pair of parallel rods 29, which may be locked in place by removable cross-pins or screws 38. The rods 28 support a leaf spring 3! which is slightly bowed upwardly to hold the push button i l normally in raised position. A simple way to mount the spring 3! on rods 29 is to bend the ends 32 of the spring around the rods; as shown in Fig. 3. It

, goes without saying that the spring 3! is attached to the rods before the latter are mounted on the supporting posts 2?. p

The spring (it carries an insulating block 33 which may be molded as a single piece of bakelite, hard rubber, fiber and the like. The block has a central projection 3% which is provided with a slot 35 for receiving the central portion of spring 34 in a tight fit, as best shown in Fig. 5. A set-screw 35 secures the block 33 to the spring against possible slipping. Since the projection 36 of block 33 is narrow and engages only the central portion of spring 39, the block does not interfere with the movements of the spring when the button it is depressed and released. It is understood that the spring 3i is sufiiciently flexible to yield under slight pressure on button i l. The normal upward curvature of spring 35 in stantly restores the connected parts to normal position when the push button id is released. The shank 53 which carries the button it may be an integral extension of blockor it may be attached to the block as a separate piece. The ends of spring 35 are mounted on rods 25 with sufficient play to permit easy slidable a justment of the spring on the supporting rods by means of the slidable button. or finger piece it.

The insulating block as on spring 35 carries a pair of contact pieces 3'! and 33. Since these contact pieces are alike in structure, a detailed description of one will suiiioe for 39th. Referring to Fig. 6, where one of the contact pieces is shown in enlarged perspective, this contact piece consists of a U-shaped member 38 having a pair of yieldable extensions i? arranged in offset relation and terminating in contact shoes 5!. The ends of the insulating block 33 are slotted at 2 to receive the base or bridge :33 of each U-shaped member 38. One or more pins, bolts or rivets fit securely connect the contact pieces 3'? and 38 to block 33. The U-shaped members can be stamped from sheet brass, and the extensions (it are preferably bent outwardly to provide sufl cient resiliency for the contact shoes 5 5. The contact pieces 3? and 38 carried by the insulating block may be of any other practical construction than the one which I have just described in detail.

The insulating base 25 is provided at the center with a longitudinal bridge or platform which is preferably integralwith the base, although it may be attached to the base as a separate piece. The insulatingbridge lscarries a pair of contact rails or barstt which may be strips of sulating bridge 55 also carries a third rail orbar s? and a series of individual contacts 8. These contacts represent the selected stations A-K and are therefore arranged in alignment with the indicating marks or lines 65 on top of the control box. This will be clear by comparing Figs. 1 and 2. The separate contacts 38 are securely held in properly spaced slots in bridge d5. Binding screws 49 are. connected to contacts it for attaching conductors 58. The three contact bars 55 and ll and the individual contacts 33 are jammed so tight in their respective slots that no separate fastening means is necessary, although screws and the like may be used for that purpose if desired. One end of each bar may project beyond the bridge 35 to permit the easy attachment of conductors El, 52 and 53, as shown in Fig. 2.

Referring to Fig. 3, it is seen that when the button it is pushed down, the contact fingers dd of connecting piece 3? engage the two insulated rails t6. At the same time, the contact fingers 4d of connecting piece 33 engage the rail ll and one of the individual contacts G8. The rails it and connecting piece Bl constitute a switch in the circu t of an electric motor that drives the tuning shaft of the radio receiver. When the connecting piece spans the rail ll and a selected contact 32, an electromagnet is energized to open the circuit of t-e motor. The control of the motor circuit will be described later on. The contact shoes ll of spring fingers it? on switch pieces 3'? and 3S adjust themselves individually to any inequalities in the upper surface of rails 55 and @l and contacts This automatic adjustment of spring fingers insures good electrical contact between the shoes at and the associated switch terminals in bridge when the finger piece it is pushed in.

I may provide means to prevent the button it from being pushed in unless the pointer ll is substantially in line Wlbh one of the station marks l5. For this purpose the insulating bridge is provided along the center with spaced lugs The insulating block 33 carried by spring has a central projection adapted to enter he space between a pair orlugs 54 wh n the say 14 is depressed. The corners of lugs 5% and projection may be rounded or bevelled to permit easy entrance of the projection into space 54. This operation, however, can not talie place unless the pointer ii is substantially in line with one of the station marks Therefore, when the button l 'i free to be pushed in, the operator is assured that it is in correct position for the selected station. Fig. 5 shows that the projection 55 of block 33 is correctly positioned between a pair of lugs If the projection should be moved slightly to one side or the other (w would mean that the pointer it is oi? the station marks), the key E l is locked against operation, exceptperhaps for a slight initial movement which is of no consequence. The bottom or" projection is normally held by spring 35 above the top surface or" lugs so that the finger piece It is always free to be shifted along the station indicator.

One end of control box it has a recess chamber 5%, whi h may be lined with heatinsulating material such as asbestos, cork, compressed wood pulp, earth nware and the like. A bracket 58 secured to base 25 by screws carries a screw and a lug El on the base supports a screw 62 in line with screw 68. The two aligned screws 5% and 62 form bearing pins for a Usliaped frame The sides of this frame may be metal pieces connected by an insulating plate or" baltelite or other suitable material. A contracting coil spring 65 is connected at its ends to bracket and plate 65. as best shown in Fig. 7. A lateral hollow lug on frame is screwthreaded inside to receive ascrew 37 extending from finger piece it. This makes it a very simple matter to disconnect the ringer piece it from the pivoted switch frame fill when it is necessary to remove the cover portion of box it from the base The insulated plate as c two pairs of switch contacts 58 and we may conveniently be the rounded heads of bolts passing through the plate and secured by nuts 59. These bolts and nuts may also used as binding posts for the contacts.

It is evident from F 2 that the pivoted switch frame is a snap-over member actuated by spring $5 with an abrupt movement from one position to the other, and the spring holds the switch securely closed and open. When the switch moved to oiT position, projection it on plate ii i strikes a spring arm ll moves it away from a stationary contact The spring arm ll is mounted at one end on lug or post 12 projecting from base 25, and the free end of this arm is normally held engagement with con act l2, which is mounted on a suitable bracket i" The members i5 a secured to base 25. and I2 constitute a normally closed switch, for a purpose that will presently be explained. The dotted outline 2'2" shows the switch arm Z! in open position, the dotted outline indicates the position of projection l9 when the switch is open.

A thermostat bar is rigidly mounted at one end on a block ?5 projecting from the bottom plate 25 or" the control box. One or more screws or bolts '56 hold the thermostat bar rigidly connected to the block. The thermostat bar i is of usual bimetallic construction. (for example, brass and iron) is preferably iJ-shaped or curved at the secured end. This curved form of the bar gives a greater freedom of movement, but any other practical form and type of thermostatic element be used. An insulated heating coil T5 is mounted on thermostat bar 14. One meth od of mounting the coi to wind heating wire on a sheath or cove-ling 58 f asbestos fibers. This wire need not be insulated, but care should be iolzen that the turns of the wire do not touch each other. If the wir is wound tight over the the individual turns sink into will remain permanently in using the insulating mounting may use insulated wire wound nostat bar it, and any other asbestos coveri the sctt lli'36l'S 7. ac real e it may be employed to support the cell i? in proper heating relation to the therinc tat a Nichroine wire is particularly emheating coils, and only a few turns of a necessary for the required heating ar When the switch is in on position and no currei assing through coil 5?, the free end of "inc-stat bar "5-, en ages the two pairs of insucting coil spring holds the contacts in pressure engagement with thermos at bar 5Q. To prevent undue wear on the oft metal of the tl". .-v I provide the atter with a plate 5'9 of hard yet good conducting tal to engage the s lltacts S2 and 5 3. e switth plate r not be insulated from er 1 i1" latter is properly insu- As will subsequently ear, the contacts are in the circuit of the motor that operates the tuning and the contacts are in cluded in the power supply circuit to form a real i on on" switch for the radio receiver. If a particular circuit arrangement so requires, eaci pair of contacts and be closed by a separate insulated plate iii. Both pairs of contacts need not be mounted on the same member, and any other ractical construction of motor switch and main switch -may be used.

to 2, it is apparent that, as long s the thermostat bar "it in normal position, switch is free to be moved by the finger iece 43 from one position the other. Let us assume that the coil l? is in circuit. As inostat bar l4 increases,

frame quickly to of position. movement of and no use p us to 1 The switch A however, remains open until closed by means of the finger piece The length or required to the *l niostat bar it; until it reacl 1 ion manifestly de, ends on e electric current flowing through coil Z23. Tobe more accurate, the heating effect of this coil is proportional to the square of the current. Therefore, as the current in coil l? is decreased, a correspondingly .longer time is required to heat the thermostat bar to switch-operating temperature, and vice versa.

Referring to Figs. 2 and 8, a simple way to regulate the current in heating coil ll is by means of a resistance 88 controlled by the timing knob 2!. The resistance wire 8% is wound on an annular insulating core 3i secured to the base 25 in any practical way, as by screws 82. A fixed metal post 83, connected to base 25 by a screw 83' or otherwise, supports an insulating shell 84 for rotary movement. The shell 8% may be a molded piece of bakelite, hard rubber, porcelain, and the like. An annular groove 85 in post 83 receives the end of a spring-pressed pin 86 carried by a hollow set-screw 87 mounted in shell 85, so that the shell is free to rotate on the post and is locked against axial displacement. A small coil spring 538 in set-screw Si holds the pin 88 pressed lightly against the bottom of groove 85. If it should be necessary to remove the shell 8 from post 83, the set-screw 8? is taken off. The screw 8'! may also be used as a binding post. The insulating shell 35+ carries a resilient contact arm 39 arranged to bear with a pressure contact on the top of resistance coil 88. The contact arm 89 has an extension 95 adapted to receive one or more screws 95 for attaching the arm to shell 8 An insulating extension 8 on shell 84 is adapted to open a switch arm 34a when the rheostat arm 89 strikes a shoulder 82 on core 8i. That happens when the pointer 22 (see Fig. l) is in 01f position 26. The switch arm Elsa may be a spring blade secured at one end to a lug Mb on base 25, and at its free end normally engaging a fixed contact 82c suitably mounted on the base.' The switch arm 84a is only a light spring which is incapable of moving the rheostat arm 89 away from the stop shoulder 32 on account of the spring pressure with which the rheostat arm bears down on the top of core 8!.

Still referring to Fig. 8, one end of resistance coil 3c is attached to a conductor 92, and a conductor 93 (which may be a short metal strip) is connected at one end to extension 9B of contact arm as. The other end of conductor 93 is secured to a binding post 9&- mounted on shell'ii l and at its inner end in permanent contact with a metal cup 95, which is firmly seated inside the shell. The binding post 95 is in the form of a removable screw which also holds the cup 95 rigidly in place. A cylindrical extension 96 on cup 95 acts as a socket for receiving a small electric lamp 9?. One terminal of the lamp is in contact with the metal socket 96, which in turn is electrically connected to binding post fi l. The

insulated central terminal 93 of lamp 97 is in' permanent contact with a metal thimble 99 mounted in an axial opening 19E! of shell 86. A coil spring lill of conducting metal holds the thirnble 99 pushed against the central lamp contact 93. The lower end of spring till rests in a metal cup Hi2, which is always in good electrical contact with the metal post 83. A flexible conductor attached to the rotary shell 86 by screw 8? is electrically connected with lamp contact 88 through the metallic parts 99, Nil, I82, 83 and. 85.

The rotary timing knob 2! is mounted on an annular extension E83 of shell 34. It is necessary that this mounting permit removal of knob 21 and yet lock the same to shell 8 for rotation of the latter when the knob is turned. The releasable locking engagement between knob 29 and shell as is effected in the present instance by providing the shell'extension 5% with one or more axial ribs i8 3 arranged to enter slots H15 in the lower end I85 of knob 21. The ribs 5% fit with suficient tightness in slots Hi5 to prevent loosening of the knob on the supporting shell 85. To remove the knob, it is only necessary to give it a good pull. There is no occasion for removing knob 2! except when the signal lamp 9i has to be replaced, or the box opened. A lens it? acts as a cap or cover for knob 25 and lets the light of lamp 9? shine through. It is usual to have the lens iii? of a bright color, like red or green, so that the operator can easily see whether the timing control is on or off. A split ring E9? or other suitable means retains the lens Eel in place. The pointer 22, which moves with the knob 2! over the time scale 23, may be mounted on the knob itself. If this knob is of molded material, such as bakelite, rubber and the like, the pointer 22 may be formed as integral radial projection to theknob. In this way the pointer is out of th way when the knob 25 is removed to permit opening of the control box. In the broader aspect of my invention, any other practical means may be provided for controlling the rheostat resistance 85 by the rotation of knob 25 or other movable finger piece. It should be noted that the pointer 22 on knob 2i is always in line with rheostat arm 89.

I now shall turn to Figs. 9-14, which show the tuning mechanism controlled by the sliclable push button it on the control box. In the present instance I have assumed that the receiver contained in radio cabinet 563 has three condenser units W9, which have their movable electrodes mounted on separate shafts H8, H2 and H3. The central shaft H3 carries a pulley lit connected by belts H5 and M5 to pulleys M8 on the side shafts Hi! and H2. In some radio sets all the tuning condensers are mounted on the same shaft and the number of condenser units varies in different makes of receivers. For brevity I shall refer to shaft l is as the tuning shaft, by which I mean broadly any shaft operable to control suitable tuning elements in the receiver. It is immaterial in my invention what kind of tuning elements are used, or how they are arranged and mounted in the cabinet. The tuning shaft H3 is manually operated by means of a rotary knob l H arranged at the front panel l E8 of the radio cabinet. To simplify the drawings, I have shown the knob i ll attached directly to the outer end of shaft H3, but in practice it is customary to provide a reducing connection between those two parts. A bracket i ii! is rigidly mounted on a base board lift in the radio cabinet by screws or bolts 629 passing'through a lateral extension l22 of the bracket. The upper end of bracket l i9 has bearings 523 for the condenser shafts H6, H2 and H3. The front ends of the two side shafts H9 and H2 are supported in bearing brackets Ill) and H2 which may conveniently be attached to the front panel i la. The parts I I9, I22 and 123 may be a single casting of aluminum or other suitable material.

The tuning shaft H3 passes through a post. or bracket H25, and the rear end of the shaft carries a bevel gear I25, which is rigidly connected to the shaft in any practical way. The bracket i213 may be an integral extension of a plate 26 secured to the bottom board E28 by screws or bolts l 2'1. The plate I25 is also provided with a pair of upright arms 523, which terminate in bearings M9 for supporting a transverse shaft lStl. Two mutilated bevel gears lSi and 832 are fixed on shaft its and arranged on opposite sides of bevel gear 25. A sleeve I33 of correct length may be mounted on shaft between gear members and facilitate their proper spacing. The mutt ted gears 53E and 532 have teeth extending for approximately half a circumference, but the teeth of one gear are arranged diametrically opposite to those the other For 0011' ience I shall refer to these mutilated bevel gears as half -gears. W h r the teeth of one half-gear move out of in n with the bevel gear the teeth of the other half-gear begin to engage the central gear reverse the rotation of tuning shaft means may be employed to prevent axial shifting of the hollow shaft i its A footplate Hi5 forming pat of bracket 538 is secured to the baseboard by screws or bolts lei. clutch ring it? is slidably mounted on shaft lZ-i'i, but rotates therewith. A simple way to lock the clutch ring 5 12 slidably to shaft 237 is to have a set-screw 53 on the clutch ring engaging in an groove or slot 144 in the shaft. An annular groove Hi5 clutch ring l 2 receives a pair of rollers or lugs M8 mounted on yoke arms i l? of a double bellcrank A lateral extension M9 on one of the upstanding arms 528 carries a pin or stud ififi on which the bellcrank M8 is pivoted. A contracting coil spring i5l is connected at its upper end to a lateral arm i552 of bellcrank M8, and the lower end of the spring is attached to the bottom board l2d in any practical way, as by a screw-eye 153. The normal tendency of spring iSl is to hold the slidable clutch ring hi2 away from the adjacent clutch member I54 fixed on shaft I30.

Referring to Fig. 11, a solenoid coil !55 is fixed on a suitable block or shelf 155, which may form an integral part of the adjacent post E28. A magnetic core it? is pivoted at 258 to a lateral arm or extension id?) of bellcrank i 13, and this core extends normally partway into coil let. The aligned shafts i3 3 and lSl are normally disconnected, so that either may be rotated without actuating the other. When the coil 155 is energized, it pulls down the magnetic core 15'. and thereby rocks the bellcrank S48 counterclockwise to throw the slidable clutch ring 142 against the associated clutch member lta i. The shaft 130 is thereby coupled to the driving shaft 53?, which is always in bearing its and clutch ring 1.42.

with which the clutch ring is normally held against the anti-friction washer tee by spring lEl is not sufficient to interfere with the free rotation of shaft ltl.

The foot-plate 522 of bracket l l9 carries an electromagnet comprising a coil and a magnetic core (see Fig. 14). A pivot pin or stud 363 projecting rearwardly from bracket lid supports a lever 565. One end of this lever carries an armature piece E65 arranged to be attracted by the electromagnet when coil ldl is energized. The other end or" lever I54 carries an insulated contact #63 which is normally held against a fixed contact i8? mounted on a bracket 38. This bracket may conveniently .be attached to the upright bracket by screws I69 or otherwise. A contracting coil spring H0 attached at its upper end to lever i8 3 normally holds the insulated contact I65 pressed against the stationary contact 55?. The lower end of spring Elli is connected to foot-plate E22 by a screw-eye ill or otherwise. it is clear from Fig. 14. that the tensioned spring ilii normally holds the armature S65 away from the magnetic core 582. When the coil i6! is energized, the electromagnet pulls down the armature E65 and rocks the lever ifi i clockwise to separate the switch contacts 555 and Hil As I shall presently explain, these contacts are included in the circuit of motor i333. The operation of lever 16 by the magnet coil I6! is so quick that the switch l-Eifi-l E? is opened without arcing.

Referring to Figs. 9, l0 and 11, the post or bracket E25 carries an insulated plate or disk H2 secured by screws H3 or otherwise. The plate H2, which is shown in the form of a half-circle, may be molded of bakelite, fiber, porcelain, hard rubher, or any other suitable insulating material. As explained in conection with Fig. 1, it has been assumed that the remote control box connected to the radio receiver is capable of selecting ten different stations. For this reason the insulating plate H2 carries ten individual contacts H4 which are radially so arranged as to represent the ten stations identified by the indicator on top of the control box. The contacts lit may be thin brass plates set firmly in radial slots cut in the edge of the semi-circular disk H2. If the contact pieces are forced into the slots to make a tight fit, no ad- 'itional fastening means are needed, although such may be employed if desired. It will be recalled (see Fig. 2) that conductors 5e are connected to the station-selecting contacts $8 in the control box. These conductors are also connected to the corresponding contacts l'id, which may be provided with tails or projections I15 for easy attachment of the conductors.

When the individual contacts in are mounted in slots arranged in predetermined radial position, each contact remains for the particular station which it represents. It may sometimes be desirable to change the radial position of one or more contacts to represent other stations than those originally indicated on the control box. One way of easily effecting a radial adjus ment of contacts H4 is shown in Figs. lia and 11b, where the contacts are provided with lateral extensions H5 and ll! adapted to engage the top and bottom of a peripheral flange M2 on disk H2. In other words, the contacts H4 are like U-shaped clamps which grip the flange H2 and may be shifted radially to any desired position. A set-screw ill may be used to secure each contact in adjusted position, and at the same time the screw may serve as a binding post for a conductor.

The tuning shaft H3 carries an insulating hub or collar H3 which is securely held in position by a set-screw H9, or in any other practical way. A metal sleeve 58B mounted on the insulating collar H8 carries'a contact arm l8i. A cylindrical extension or base 582 of arm i8i fits over the metal sleeve I and is secured thereto by screws l 83, which also fasten the sleeve to the insulating hub l'it. The arm lad is sufiiciently resilient to press against the contacts lid. A spring finger i mounted on an insulated bracket i bears constantly against the conducting ring Hill. The bracket 885 may be attached to post I25 by screws I85 or otherwise. The parts E80, 58! and i8 3 may be of brass, bronze, or other good conducting metal.

Referring to the circuit connections in Fig. 15, the station-selecting contacts 48 in the control box and the corresponding contacts H4 in the radio cabinet are differentiated by the suffix letters a to k. This makes it easy to identify the individual contacts 58 and I'M with the different stations marked on the control box (see Fig. l) Thus, a glance at Fig. 15 indicates that the connected contacts 43a and il la refer to station A on the control box, that contacts 331) and H4?) refer to station B, and so on for the remaining contacts and stations. The individual conductors 55 which connect contacts 48 and lid aredistinguished by the suffix letters a to It to facilitate the tracing of circuits. For the same reason one of the contact rails 46 is marked 45 in Fig. 15. A plug I37 adapted to be inserted in a wall socket carries a pair of service leads E88 and I39. 'A conductor E99 connects lead 588 with the motor terminal WI. The other terminal 592 of the motor is connected by a conductor 93 to one side of the clutch coil I55, the other side of which is connected to conductor 5!. The motor windings and clutch coil E55 are therefore connected in series through the switch bars d5t'. Any other practical connection may be used for simultaneously energizing and de-energizing the clutch coil and the motor. A conductor 5% connects the contact finger or brush 584 to one of the contacts 68 on the snap-over switch frame 63 in the control box. The insulated contact E65 mounted on the pivoted lever M54 is connected to conductor 52, which is also connected to switch bar it in the control box. Thestationary switch contact it? is connected to conductor 1% by wire E85.

Still referring to Fig. 15, it will be seen that one side of the thermostatic heating coil ii is connected to conductor 32, which leads from one end of rheostat resistance 85 to the stationary switch contact 72. The other side of heating coil i1 is connected by conductor E to binding post I 96 to which the conductor 93 is also connected. A conductor i9? leads from the service main 188 to switch arm tea, and conductor 19? connects the switch contact 840 to binding post 8? and thereby to the central contact 98 of signal lamp 9?, as previously explained. It will also be remembered that the metal socket '95 of the lamp is connected by conductor 93 to the rheostat arm 89. It is thus evident that the heating coil ii is shunted by resistance 89, and that the lamp 9? is in series to those two elements. This particular connection of lamp 9? is not necessary, but it has the practical advantage that the lamp burns with substantially constant brilliancy without regard to the position of rheostat arm 39 (except when the'time control is a receiver to the power mains.

off). It is usually desirable to shunt the signal lamp 9? by a resistance 93, so that the timing mechanism will not be put out of commission if the lamp should suddenly burn out. The movable switch arm H and one of the contacts 68 on the pivoted switch frame 63 are connected to the service main 189. A pair of terminals S99 is supposed to lead to the radio receiver for connecting the same in the power supply system when plug i8? is inserted. The contacts 68' mounted on the pivoted switch member 63 are shown separately in Fig. 15 to avoid confusion in the arrangement of the circuit lines. The radio terminals ltd are connected to the power mains by conductors 258 and 25! and the switch contacts 58 are inserted in series in conductor 25!. Branch wires 252 are connected to conductor 25! in shunt to contacts 68' and lead to a suitable hand switch 253, which is supposedto be mounted on the radio cabinet for turning the, set on and off independently of the control box. In other words, if the switch frame 83 in the control box is in off position, a person may still opcrate the receiver by closing the hand switch 263.

Conversely, if the hand switch 293 is open, a per-.

son may operate the receiver through the control box by. moving the finger piece 53 to on position.

The operation of the radio receiver through the control box' it is like this: We shall assume that the timing knob 2l'is in off position 24 and that the finger piece it is in on position, so that the switch 63 is closed to connect the radio Let us further suppose that the operator wants to tune in station D. The button it is moved along the slot !2 until the pointer i? is in line with the indicating mark D of the selected station. When the button it is pushed in, the circuit of motor I33 and clutch coil I55 is closed through the following connections: Service main H38, conductor I96, through the motor windings and clutch coil E55, conductor i5i, across the two switch bars at and 46 which are now connected by contact piece 31, conductor 52, closed switch EEG-467, conductor E84, and across the closed switch contacts 68 to the return lead 58$. The energized solenoid coil I55 shifts the clutch ring M2 to connect shafts i3? and ESQ. -The energized motor E33 drives the tuning shaft 53 through the automatic reversing mechanism previously described. The reduction of speed in these transmission connections is such that the tuning shaft moves at the required slow speed.

When the rotary contact arm l8! contact Wild on disk-5'52, the magnet coil i6! is energized through the following connections: Circuit main E88, coil EBI, conductor 53, across bar ii and contact 13d, which are now connected by contact piece 38, conductor 56d and contact ii id, arm l8l, brush i8 5, conductor I94, and across the closed contacts 68 to return main M58. The energized coil iEi rocks the lever 584 to open the switch contact 168, so that the circuit of motor E33 and clutch coil H55 is instantly opened, and the condenser shaft H3 stops in tuning po sition for the selected station D. As soon as the operator hears the broadcast through the loudspeaker of the radio set, he releases the push button M which instantly snaps back to normal position. The release of button it breaks the circuit of coil I (it, so that the switch contacts ltd-451 in the motor circuit are again closed. This, however, does not close the motor circuit,

touches because the terminal bars 46 in the control box are disconnected when the button is released. There is no need to trace the circuits for each station, because the operation of the mechanism is the same for any station, except that the tuning shaft is stopped when the rotary contact arm tel engages with the particular contact H that represents the station indicated by push button i i. For example: if the push button is moved to select station G, the circuit of motor 233 is broken when the contact arm lsl touches contact ii -lg. This applies to all the. other stations. Attention is called to the fact that the timing shaft H3 stops instantly on th release of key i i, because not only is the motor stopped, but the shaft I35 is disconnected from shaft 53? by clutch ring M2. Therefore, continued rotation of the motor shaft through its own momentum after the circuit is opened, has no effect on the tuning position of shaft MB.

In the preceding description, we have assumed that the time control is on", so that the thermostat bar remains stationary and performs no other function than that of a stationary contact piece for the pivoted switch frame 53. Let us now assume that the timing knob 2! has been moved to an operative position along the time scale 5 .3. When the rheostat arm 88 is in position practically all the resistance 85 is in circuit, so that the current through coil Z1 is a maximum. This means that the thermostat bar is heated very rapidly, so that the main switch is opened after a minimum interval of time, which is conveniently represented on the. timing scale of the control box by the numeral I. This does not necessarily mean one minute, but rather the briefest interval during which the radio set will remain in operation after the pointr of knob has been moved to the first division on the tining scale. As the arm 8% is gradually turned clockwise to cut out more and more resistance, the current through coil TI is correspondingly decreased. Consequently, it takes longer for the thermostat bar '24 to become heated high enough to operate switch 63. When the pointer 22 of the timing knob 25 is at the highest point on the scale, the rheostat arm 89 is in position 8% to cut out almost all the resistance So, so that only a weak current flows through coil TI. The heathi effect of the coil now accumulates so slowly that it ta 'es a maximum interval of time to heat the thermostat bar '54 to switch-operating temperature. When the pointer 22 is in line with the ofi mark (see Fig. l), the extension 3 3- of shell (see Fig. 2) opens the switch arm 3 2a, so that the circuit of heating coil ll, resistance 8d and lamp Si is broken.

The electrical conductors that connect the remote control box 4 with the radio receiver are enclosed in a single cable 204 (see Fig. 2). If it is not desired to have the full house-lighting voltage in the cable, the switch contacts 68' may be connected a relay circuit of low voltage for closing the switch 283 in the radio cabinet when the relay is energized. The other conductors the cable need not carry the full voltage of the house-lighting system, because only a low voltage is required to operate the heating coil ill and the signal lamp 91' in the control box, and to operate the electric motor 33 and coils 555 and H55 in the radio cabinet. The circuit connections for controlling the volume of reproduction by knob 25 have been omitted, because they form no part of my invention and are furthermore understood by those skilled in the art.

I have only considered it necessary to indicate a rheostat 205 in Fig. 2 under the control of vol ume knob 23. The cover part of control box 56 may be of suitable color and design, and the same applies to the hand-operable parts l4, i8, 28 and 29. he signal lamp 9'. may be mounted independentiy of timing knob 2|, but the arrangement shown is believed to enhance the attractiveness of the box as a whole. In a simplified form of my invention the timing mechanism may be omitted. The control box may also be mounted on the radio cabinet itself for automatic tuning without remote control. It should be noticed that the receiver is always in condition to be tuned by hand in the usual way, because shaft 236 is normally disconnected from the motordriven shaft 13?.

If the resistance 3b is made of metallic wire, it will of course give 01f heat, but this will not appreciably affect the thermostat bar M. In any case, however, the timing scale 23 can be calibrated to compensate for any heating effect of resistance 89. It should be noted that the scale 23 need not be accurate to the exact minute, for only an approximation of time is necessary for practical purposes. The controlling resistance 89 may also consist of carbon or graphite, or of any other practical material. Furthermore, the chamber 55 may have ventilating holes, preferably at the sides.

Although I have shown and described certain specific constructions, I want it understood that my invention is not limited to the details set forth. Changes and modifications will probably occur to others within the scope of the invention as defined in the appended claims.

I claim as my invention:

1. In radio tuning apparatus, a remote control box adapted to be operatively connected with a radio receiver, a SWll/Ch in said box for closing the circuit of said receiver, means independent of said power switch selectively operable for tuning in any one of a plurality of stations, a rotary knob mounted on said box, a time index associated with said knob, and thermostatic means controlled by said knob for automatically opening said switch after a predetermined interval, this interval being varied by the adjustment of said knob in relation to said index.

2. A radio receiver having variable tuning mechanism which includes a rotary member movable to any one of a plurality of angular positions representing each a certain station, in combination with a remote control box operatively connected with said mechanism and hav ing means for selectively controlling said mechanism to stop said member in tuning position for anyone of said stations, a hand-operable switch in said box for turning the receiver on and off, thermostatic means in said box for automatically opening said switch after a certain lapse of time, an adjustable finger piece on said box, and means controlled by said finger piece for aiiecting the operation of said thermostatic means to vary said time interval.

3. A radio receiver having variable tuning mechanism which includes a rotary member movable to any one of a plurality of angular positions representing each a certain station, in combination with a remote control box operatively connected with said mechanism and having means for selectively controlling said mechanism to stop said member in tuning position for any one of said stations, 2. hand-operable switch in said box for turning the receiver on and oil, adjustable thermostatic means in said box for automatically opening said switch after a certain lapse of time, and hand-operable means for rendering said thermostatic means inoperative to affect the closed and open positions of said switch.

4. A radio receiver having variable tuning mechanism which includes a rotary-member movable to any one of a plurality of angular positions representing each a certain station, in combination with a remote control box operatively connected. with said mechanism and having means for selectively controlling said-mechanism to stop said member in tuning position for any one of said stations, a hand-operable switch carried by said box for turning the electric power on and off, a thermostat bar in said box for automatically opening said switch after a certain lapse of time, a heating coil for said bar, and manually adjustable means carried by said box for regulating the current through said coil to vary said time interval, said last-mentioned means being operable-to out said heating coil out of circuit and thereby render said thermostat bar inoperative in relation to said switch.

5. In combination with a radio receiver having tuning mechanism, a remote control box operatively connected with said mechanis:i said box having a single finger piece adjustable in a substantially rectilinear path to any one of a plurality of positions, each of which represents a certain station, a slidably supported spring blade mounted wholly within said box for supporting said finger piece so that it can be pushed in, switch mechanism controlled by said finger piece when the same is pushed in, and means whereby the pushing-in operation of said finger piece automatically causes said switch mechanism to control said tuning mechanism so as to tune in the particular station re resented by the rectilinear position of said finger piece, said resilient means automatically raising said finger piece to normal position when it is manually released.

6. In combination with a radio receiver having tuning mechanism, a remote control box operatively connected with said mechanism, said box having a straight slot on top, a single finger piece projecting through said slot and mounted to slide in either direction to any one of a plurality of positions, each of which represents a certain station, means whereby said finger piece is depressible, said finger piece being normally in raised position, a series of switch contacts in said box represen ing each a selected station, switch means operated by said finger piece to en age one cfsaid contacts when the finger piece is pushed down, means whereby the engagement of said switch means with a selected contact automatically operates said-mechanism to tune in the station represented by the engaged contact, and a slidably supported spring blade mounted entirely within said for automatically raising said finger piece to normal position when it is manually released.

7. In combination with a radio receiver having tuning mechanism, a control device operatively connected with said mechanism, said device having a pair of parallel supports, a spring member slidably mounted on said supports, a push button connected to the center of said spring member for sliding the same to a selected position, said spring member normally holding said button raised, and normally open switch mechanism adapted to be closed when said button is depressed in any adjusted position.

8. In combination with a radio receiver hav ing tuning mechanism, a control device operatively connected with said mechanism, said device having a bowed leaf spring slidably supported at its ends, a push button connected to the central portion of said spring for sliding the same, said spring normally holding the button in raised position, a station indicator associated with said button, and normally open switch mechanism adapted to be closed when the button is pushed in to bring in the selected station.

9. In combination with a radio receiver having tuning mechanism, a control device operatively connected with said mechanism, said device having a station indicator comprising a series of marks representing each a selected station, a push button movable bodily along said scale and normally held in raised position, a pointer movable with said button to select a desired station, operating circuits controlled by said button when the same is pushed in, and means for preventing inward operative movement of said button unless saidpoint substantially in line with a station mark on said indicator, said last-mentionet means permitting free sliding movement of the push button in normal raised position.

10. In combination with a radio receiver having tuning mechanism which includes an electric motor, a remote control box operatively connected with said mechanism, said box being provided with a push button which is slidable to a plurality of selected positions, each position representing a certain station, a motor switch in said box adapted to be closed when said button is depressed in any one of its positions whereby said tuning motor is energized, a plurality of stationselecting switches in said box adapted to be individually closed by the depressed button to stop said motor in selected tuning position, there being a selecting switch for each position of the button, spring means within said box for normally holding the button raised in any position to keep all of said switches open, said spring means automatically raising the push button to'circuitopening position when the button is released, and means for mounting said button to permit free sliding movement thereof in normal raised position.

11. In radio tuning apparatus, the combination or" a hand-operable switch member for closing the power circuit for the receiver, a finger piece for moving said switch member to closed and open positions, means independent of said power switch and selectively operable for tuning in any one of a plurality of stations when said switch member is in closed position, means for automatically moving said member to open position after a predetermined lapse of time, wher by the selected station is cut out, and a hand-operable member independent or" said finger piece and station-selecting means for varying said time interval and for rendering said automatic switchoperating means inoperative.

12. In radio tuning apparatus, the combination of a pivoted switch arm, a finger piece for moving said switch arm to closed and open positions, means independent of said switch arm and selectively operable for tuning in any one of a plurality of stations when said switch arm is in closed position, means for automatically swinging said arm to open position after a predetermined lapse of time, whereby the selected station is out out, and a manually operable member for varying said time interval.

13. In radio tuning apparatus, the combination of a hand-operable switch member in the power circuit for the receiver, a finger piece for moving said switch member to closed and open positions, means independent of said switch member and selectively operable for tuning in any one of a plurality of stations when said switch member is in closed position, thermostatic means for automatically moving said member to open position after a predetermined lapse of time, whereby the selected station is cut out, and a rotary hand knob for controlling the operation of said thermostatic means to vary said time interval.

14. In radio tuning apparatus, the combination of a hand-operable member in the power circuit for the receiver, a finger piece for moving said member to close and open said circuit, means independent of said member and selectively operable for tuning in any one of a plurality of stations when said member is in circuit-closing position, means for automatically moving said member to circuit-breaking position after a predetermined lapse of time whereby the selected station is cut out, and a second hand-operable member for controlling the operation of said means to vary said time interval.

15. In radio tuning apparatus, the combination of a hand-operable switch member in the power circuit for the receiver, a finger piece for moving said switch member to closed and open positions, means independent of said power switch and selectively operable for tuning in any one of a plurality of stations when said switch member is in closed position, thermostatic means for automatically moving said member to open position after a predetermined lapse of time whereby the selected station is cut out, and hand-operable means for controlling the action of said thermostatic means to vary said time interval.

16. In combination with a radio receiver having tuning mechanism, a device operatively connected with said mechanism for controlling the same to select any desired station, said device comprising a spring-pressed push button movable to any one of a plurality of station-selecting positions, switch means operated by said button when the latter is depressed in any one of said positions, and means for locking said button against being pushed in when it is not in correct station-selecting position, said locking means permitting free movement of the push button in normal position to any station-selecting position.

17. In combination with a radio receiver having tuning mechanism, means for controlling said mechanism to tune in any desired station, a hand-operable switch for turning the receiver on and off, said controlling means being separate from said power switch and operable independently thereof, adjustable thermostatic means for automatically opening said switch after a certain lapse of time, whereby a tuned-in station is cut out, hand-operable means for rendering said thermostatic means inoperative, so that a selected station remains in tune until said switch is manually opened, a signal lamp which is lighted when said thermostatic means is in operation, and switch means for automatically opening the lamp circuit when the thermostatic time control is 01f.

18. In combination with a radio receiver having tuning mechanism, a device operatively connected with said mechanism for controlling the same to select any desired station, said device comprising an insulating base carrying a pair of parallel terminal bars, a series of separate con-,

tacts carried by said base, each contact representing a certain station, a common contact bar associated with said station contacts and mounted on said base substantially parallel with said terminal bars, a support slidable transversely of said bars and carrying a pair of insulated switch members, one of said switch members being in line with said pair of terminal bars and the other switch member being in line with said station contacts and associated contact bar, spring means for normally holding said support in such position that said switch members are out of engagement with said bars and contacts, and a push button for sliding said support to any selected position and pushing it inwardly to move said switch members into circuit-closing position.

19. A radio receiver having variable tuning mechanism which includes a rotary member movable to any one of a plurality of angular positions representing each a certain station, in combination with a remote control box operatively connected with said mechanism and having means for selectively controlling said mechanism to stop said member in tuning position for any one of said stations, a hand-operable switch carried by said box for turning the receiver on and off, thermostatic means in said box for automatically opening said switch after a certain lapse of time, and manually adjustable means carried by said box for controlling the action of said thermostatic means to vary said time interval.

20. A radio receiver having variable tuning mechanism which includes a rotary member movable to any one of a plurality of angular positions representing each a certain station, in combination with a remote control box operatively connected with said mechanism and having means for selectively controlling said mechanism to stop said member in tuning position for any one of said stations, a hand-operable switch carried by said box for turning the receiver on and off, adjustable thermostatic means in said box for automatically opening said switch after a certain lapse of time, and an adjustable finger piece mounted on said box for rendering said thermostatic means incapable of affecting the closed and open positions of said switch.

ADOLPH A. THOMAS. 

